Unloading mechanism



July 1, 1930. F. D. HOLDSWORTH UNLOADING MECHANISM Filed Dec. 31, 1925 Patented July 1, 193i) time. nonnswonrn, or CLAREMONT, new nanrrsnran, nssrenon T SULLIVAN MACHINERY COMPANY, A conronarron or nassaonusn'rrs Unmanne- MECHANISM Application filed December 31, 1923: Serial No. 683,812.

This invention relates generally to fluid exhausting means, and more particularly to means for unloadingvacuum pumps when a certain vacuum has been reached.

An object of the invention is to provide an improved unloading mechanism for a vacuum pump. Another object is to provide an automatic means for unloading the vacuum pump when a predetermined low pressure has been reached thereby making it possible to maintain a constant vacuum. A further object is to provide an improved means for controlling the unloading mechanism. A still further object is to provide improved means whereby the atmospheric pressure will be suliicient to actuate pump valves for unloading purposes.

1n the accompanying drawings I have shown "for purposes of illustration one form which my invention may assume in practice.

In these drawings, 1

Fig. 1 is a side elevation partly broken away to show the valve mechanism of the pump.

Fig. 2 is an enlarged vertical sectional de- 2 tail of the means for controlling the unloading mechanism.

In the illustrated embodiment of my in vention I have shown my improved unloading means in connection withia usual vacuum 3 pump '1 having a reciprocable piston 2 and inlet valves 3 which allow communication with the usual chamber 4 andthercylinder oi the pump while a tank 5 has communication with the chamber 41 as by a pipe 6.- It will of 3 course be understood that anytype of compressor might-be used and that the valves 3 might only, be reliet' valves. The means for unseating the valves 3 is of standard construction, one being used for eachvalve, and com prises a downwardly projecting casing ,7 having reciprocable piston mounted therein with an upwardly projecting stem 7. This construction is ofa well-known form and it will suiicev to say that when the rod 7 is forced upwardly against the bottom of the valve, it Willhold the same open. The bottom of the cylinder of each mechanism communicates with theother as by a pipe 8 which inturn has communication with a pipe 9 lead- 'ing to the controlling means 10 which in turn pipe 11.

has communication with the tank The controlling means shown in Fig. 2 controls fluid below atmospheric pressure. This means, briefly described, comprises a body portion 12 having a chamber 13 therein which communicates with the tank 5 as by pipe 11. Actuation of the controlling means is brought about by means of a diaphragm'l l disposed on the upper surface of the body 12 and covering the chamber 13. It is held in position as by a cover 15 which has an upwardly extending guide portion 16, this cover being held to the body 12 by bolts or other suitable means. A. stem 17 fixed to the diaphragm projects upwardly through guide 16 while a spring 18 which'surrounds the stem and guide tends to force the stem 17 in an upward direction as by having engagement with a nutand washer 19 adjustably screw threaded on the upper end of the stem 17. It will be noted that the cover 15 forms a chamber 20 disposed above the chamber 18 and has communication with the atmosphere as by aport 21. The remaining portion of the controlling means comprises a valve supporting member 2'7 which supports a vertically movable control valve 22 having. ports 23 communicating with a bore 28 and adapted to engage a movable plate 2st disposed in a connection 31. This plate has ports 25, and a spring 26 mounted in a bore 30 of member 31 maintains the plate in engagement with the end of the valve 22 or the lower surface of the. valve supporting member 2?. In the position as shown, the

,bore 28 is closed at its lower end by the plate 2'11 and the chamber 30 has communication with the atmosphere as by the ports 25 and passages 32 within the member 27. A recess 33 is also formed in the lower end of the member 27 for allowing communication between chambers-13 and 30.;whenthe valve 22 isin its uppermost position.

The operation of the device is substantially as follows. Assuming, that the pressure in the tank 5Vis not downto" the predetermined low pressure, the valves'8 Wlll continue to loperatenormally. Pressure in the chamber 13 of the controlling means 10 will always correspond to that in the-tank due to the oasbya connection 11. When the tank pressure has reached a predetermined low point, the pressure of the atmosphere, which has communication with the chamber as by port 21, 5 will be greater than the resisting pressure in the chamber 13 and that of the spring 18, and hence will force the diaphragm 14 downwardly against the upper end of the valve 22 thereby forcing the latter also downwordly so that the lower end thereof will abut a ainst the plate 24 as shown in Fig. 2, thus c osin the lower end of the bore 28, it bei note that the ports 25 are disposed on isfie outside of the valve member 22. It will be noted in this position that atmosphere mmmunicates with chamber as by ports 32 and 25. The pipe 9 is connected to the lower end of the connection 31 so that atmospheric pressure will be transmitted to the pipe 8 and thence to the lower side of the pistons within the cylinders from which the piston rods 7 project. The atmospheric as: on the lower side of the piston be- I ater than the pressure within the chem r 4 will raise the piston rod 7 against the lower end of the valve and hold it open. When the pressure in the tank rises above the predetermined low point, the pressure of spring 18 and the tank pressure in the chamso her 13 will force the stem 17 upwardly while springs 26 and 26' will also force the valve .22 upwardly so that the plate 24 will rest against the lower surface of the member 27 and thereby close the lower end of the pas- 32. Communication between the tank and the pipes 8 will then be reestablished as lava 11, ports 23, bore 28, ports 25 and an r 30, thus cutting off atmospheric re on the under side of the piston rods The pressure on the pistons in the cyl- 7 is now such that they will be retmcted from agement with the valves, thereby letting t e latter resume their normal operation.

While I have in this application specifioally described one form which my invenmay assume in practice, it will be underltood that this form of the same is shown purposes of illustration and that the in- .Imtmn may be modified and embodied in other forms without departing from itsvggrit or the scope of the appended claims. at I claim as new and desire to secure by Letters Patent is: 1. In combination, a vacuum pump and means for automatically unloading said pump when a predetermined pressure below atmospheric 1s reached, said unloading means including a fluid actuated unloading coomlement and a pilot valve controlling the at thereof, said pilot valve includg atmospheric port, and means for 0 engpaid port when the said predetermined mmospheric pressure is reached. 66. $23 The combination of avacuum pump, a

tank, and means for automatically unloading said pump when a predetermined ressure below atmospheric ressure has een reached in said tank inc uding a movable valve actuating member enclosed in a casin" and means whereby said member may be subjected on opposed sides to sub-atmospheric pressure.

3. In combination, a vacuum pum having valves for normally controlling ow of fluid therethrough, and control means for interrupting normal operation of said valves including a member movable to actuate one of said valves and subject on one side to subatmospheric pressure created by said ump and means whereby an opposed side of said member is adapted to be subjected to atmospheric and to sub-atmospheric pressure when the sub-atmospheric pressure created by said pump reaches difierent predetermined degrees.

4. The combination of a vacuum pump, and means for unloading the same when a predetermined pressure below atmospheric has been reached, including a valve actuating member operated by atmospheric pressure, and means whereby said member is subjected to atmospheric pressure only during the unloading operation.

5. In a vacuum producing system, a tank, a vacuum pump having its intake side connected with said tank,, and means for interrupting the exhausting of air from said tank while its communication with the intake side of said pump is maintained including a valve actuating element and a pilot valve controlling the movement of said element and responsive to vacuum conditions in said tank.

6. In a vacuum producing system, a suction line, a vacuum pump having its intake connected with said suction line, and means for controlling the exhausting of air by said pump from said suction line while communication between said pump intake and said suction line is maintained includin a valve actuating element constantly sub ected on one side to suction line pressure and means for subjecting it alternatively on its other side to suction line or atmospheric pressure.

7. In combination, a vacuum pump having valve mechanism for normally controlling flow of fluid therethrough, and control means for unloading said compressor by means of said vnlvemechanism including a member directly subject on one side to sub-atmospheric pressure created b said pump, and means including a pilot va ve whereby an opposed side of said member is adapted to be subjected to sub-atmospheric pressure when the sub-atmospheric pressure created by said' pumpreaches a predetermined degree.

' 8. In a vacuum producing system, a suction line, a vacuum pump having its intake connected with said suction line, and means for controlling the exhausting of air by said pump from said suction line while communication between sald pump intake and sald suction l1ne is maintalned mcludmg a valve actuating element constantly subjected on one side to suction line pressure and means including a pilot valve responsive to suction line pressure for subjecting the opposite side of said element selectively to different pressures in accordance with variations in said suction line pressure.

9. In a vacuum producing system, a suction line, a vacuum pump having its intake connected with said suction line, and means for controlling the exhausting of air by said pump from said suction line while communi cation between said pump intake and said suction line is maintained including a valve actuating element constantly subjected on one side to suction line pressure and means for subjecting it on its other side selectively to different pressures in accordance with variations in said suction line pressure.

10. Unloading means including a valve operating element, means for subjecting one side of said element constantly to the pressure conditions controlled by the unloading means, and means for subjecting the other side of said element selectively to said pressure conditions or to atmospheric pressure dependent upon variations in said pressure conditions.

In testimony whereof I affix my signature.

FRED D. HOLDSWORTH. 

